Selection and techno-economic analysis of hybrid ground source heat pumps used in karst regions

Abstract

In order to take advantage of different forms of heat pumps and to mitigate thermal imbalance underground caused by long-term operation of ground source heat pumps, hybrid ground source heat pump systems have received an increasing attention. In this research, based on the fact that abundant groundwater resources are commonly available in karst regions, a new strategy is introduced for selecting and determining hybrid ground source heat pump capacity. Five scenarios of hybrid ground source heat pump system coupling groundwater source heat pumps with other supplementary heat pumps are proposed in this article to provide appropriate options to eliminate heat buildup under different hydrogeologic conditions. Methodologies for sizing and selection are established. Then, a case study of techno-economic analysis was performed for a project in the karst region in South China. The results showed that these scenarios can effectively mitigate heat buildup, and under the hydrogeologic condition in the case study. Compared to the solo ground-coupled heat pump solution, the optimal solution (Solution 4 in this study) can reduce the annual costs by 16.10% and reduce the capital investment by 60%. Methodologies developed in this study are beneficial for selecting appropriate approaches to mitigate heat buildup and enhance competitiveness of ground source heat pumps.

Research on the Application of Fracture Water to Mitigate the Thermal Imbalance of a Rock Mass Associated with the Operation of Ground-Coupled Heat Pumps

“…Y. Tian et al [9] built an analytical model to study the heating performance considering the condition of groundwater seepage and the results showed that the groundwater can mitigate the decrease in soil temperature near the energy piles located upstream. W. Zhou et al [10] proposed hybrid ground source heat pumps integrating GCHP and a groundwater source heat pump to eliminate the heat imbalance problem and to reduce investment. In engineering practice, the difference in energy between heating and cooling was restricted artificially to mitigate the thermal imbalance.…”